[Hoooper]

Ah ok so worldwide. That's good since I thought it was clear there aren't safe havens in the US. The clusters we have here are conveniently located around locations of higher population density. Not really a cluster so much as normal that where there are more 335ds there are more reports.

[Pierre Louis]

Originally Posted by Hoooper

Ah ok so worldwide. That's good since I thought it was clear there aren't safe havens in the US. The clusters we have here are conveniently located around locations of higher population density. Not really a cluster so much as normal that where there are more 335ds there are more reports.

Not true in Savannah, where at least half of known 335d's have had it, but this may not be statistically significant. Would love to get my hands on data from BMW. Still, the fact remains that other diesel brands do not have the apparent magnitude of CBU that the 335d has in NA, but I would still read into the postings with a grain of salt, as there really isn't enough information there either.

PL

[Pierre Louis]

Originally Posted by Hoooper

Ah ok so worldwide. That's good since I thought it was clear there aren't safe havens in the US. The clusters we have here are conveniently located around locations of higher population density. Not really a cluster so much as normal that where there are more 335ds there are more reports.

The dealer I bought mine from, in Charleston SC, sold a lot of 335d's. Haven't noticed anyone from there posting about CBU. Can't really tell enough with this observation though.

PL

[floydarogers]

Originally Posted by Pierre Louis

Yes, cetane seems to matter, and more so in the 335d high revving high performance "light duty" diesel, as you know BMW specifies a cetane number of 51 for this engine in NA.

Originally Posted by Hoooper

Wait I'm confused, who believes that cbu is a regional issue and why? Regional within the US or regional worldwide?

Interesting. I might speculate that the CA Emissions states have fewer problems due to slightly better cetane - that would cause a US "regional" effect.

It sort of annoys me that the Europeans are always bragging on their fuel quality; the reality is that the formulations are pretty identical and the only real difference is the delivery systems. BMW has a history of blaming fuel for their engineering problems - remember the Nikasil fiasco for UK aluminum engines, and US V8 engines?

[Hoooper]

Originally Posted by Pierre Louis

Not true in Savannah, where at least half of known 335d's have had it, but this may not be statistically significant. Would love to get my hands on data from BMW. Still, the fact remains that other diesel brands do not have the apparent magnitude of CBU that the 335d has in NA, but I would still read into the postings with a grain of salt, as there really isn't enough information there either.

PL

So you know a few 335d in Savannah, and half have had it. What % of the total of the actual number of local cars have had it, and how does that compare nationwide? Youre just making stuff up since you dont know how many cars are local and you definitely dont know the number of cars nationwide that have been cleaned. We have no data that supports any kind of conclusion that there are regional clusters beyond just the density of cars. If we could get BMW to give us that info then we could have something to go on.

Originally Posted by floydarogers

Interesting. I might speculate that the CA Emissions states have fewer problems due to slightly better cetane - that would cause a US "regional" effect.

There have been plenty of cases in CA, theres no evidence to support that there is lower CBU in CA or CA emissions states than other states.

[Pierre Louis]

Originally Posted by Hoooper

So you know a few 335d in Savannah, and half have had it. What % of the total of the actual number of local cars have had it, and how does that compare nationwide? Youre just making stuff up since you dont know how many cars are local and you definitely dont know the number of cars nationwide that have been cleaned. We have no data that supports any kind of conclusion that there are regional clusters beyond just the density of cars. If we could get BMW to give us that info then we could have something to go on.

Knowing that I doubted even my observation, which is as accurate as anyone else's since I was in touch with the dealer etc., do statements like "but this may not be statistically significant" mean anything to you, or did you not read that far....

Sorry, but we agree on this, and arguing won't help.

There have been plenty of cases in CA, theres no evidence to support that there is lower CBU in CA or CA emissions states than other states.

Yes, it would be good to see the data that BMW has on this too, as I've also said.

PL

[Mrchntmarine]

So it's crazy - just had to do walnut blasting bc of cbu and throwing codes. Also the dealer replaced no. 2 injector. We try to use all the time higher quality fuel from stations that have higher turnover. I think part of the problem may have been touched on - a little over 5yr old car with only 35,000 miles - mostly all city driving.

[Pierre Louis]

Originally Posted by Mrchntmarine

So it's crazy - just had to do walnut blasting bc of cbu and throwing codes. Also the dealer replaced no. 2 injector. We try to use all the time higher quality fuel from stations that have higher turnover. I think part of the problem may have been touched on - a little over 5yr old car with only 35,000 miles - mostly all city driving.

Sheesh. Do you know if your car had the DDE (engine ECU) updated? Late build 2011 models seem to have had the latest DDE and as I recall there was an update to the software after that, which may have been aimed at the CBU problem, dunno.

What stations qualify for "higher quality fuel from stations that have higher turnover?" McDonalds has higher turnover but many would certainly not call it "higher quality." Brand name/top tier fuel is all I would use, save an occasional Hess station.... Better ingredients, better, uh, diesel.

PL

[Mrchntmarine]

Originally Posted by Pierre Louis

Sheesh. Do you know if your car had the DDE (engine ECU) updated? Late build 2011 models seem to have had the latest DDE and as I recall there was an update to the software after that, which may have been aimed at the CBU problem, dunno.

What stations qualify for "higher quality fuel from stations that have higher turnover?" McDonalds has higher turnover but many would certainly not call it "higher quality." Brand name/top tier fuel is all I would use, save an occasional Hess station.... Better ingredients, better, uh, diesel.

PL

Yep - we have all recommended and applicable updates. In ref. to higher quality fuel from stations that have higher turnover - I should have said - top tier fuel, following suggested guidelines from BMW as much as possible from stations that get a high volume of traffic which should help ensure maybe having the freshest available fuel. In other words, not Supper Expresso's diesel out in the boonies that probably gets a tank of diesel sludge delivered once a year.

[dixy2k]

To me it's funny how a lot of people were saying CBU only happened to a very few number of 335d's, now a lot more are coming out with this problem.

[Pierre Louis]

Here is an article by a seemingly knowledgable tech that says the engine management programming has the greatest effect. Funny how EGR isn't mentioned, but he is mostly talking about gasoline direct injection.

Thankfully, managing with CBU, at least if it doesn't occur too early, is now becoming more affordable. We'll see if anyone solves this. Those that get rid of their EGR/DPF etc. will put on a bunch of miles and hopefully will not be bothered by it. We shall see.

PL

[Tomnavigator]

I would like to mention several observations I have from my diesel ownership. My diesels are 2006 vw beetle (128k) , 2004 Passat (185k) , 2004 touareg (86k), 2001 duramax (120k) , and 2010 335d (55k). Only the BMW has a particulate filter.

I have observed soot out the exhaust on all except the BMW (with particulate filter in the exhaust). The harder you accelerate the more soot is produced. Under light loads none make visible soot.

I saw a BMW chart showing EGR vs engine load. This chart showed that EGR does not occur under wide open throttle. The charts shows that EGR occurs under most engine load conditions. Therefore, It makes sense to me that the harder you accelerate (more soot produced) and with EGR, more soot will be fed back to the intake. Thus, carbon build up would be more pronounced in cars that are driven moderately hard not cars that are babied.

I would like to address the stated sources of oil in the intake. 1) (PCV) positive crankcase ventilation, 2) turbo seal leaks 3) valve seal leaks
1) PCV occurs on all vehicles even new ones
2) turbo seals don't normally leak on relatively new vehicles
3) valve seals don't normally leak on relatively new vehicles and typically leak when the intake is under a vacuum. This does not occur on diesels. With the turbo, the intake is under positive pressure at all times. Also, CBU occurs in the intake system long before the area around the valves. Thus valve seal leakage is probably not a significant source of oil causing CBU.
CBU seems to start occurring on vehicles with around 50k miles. Therefore, the probable source of oil in the intake on low mileage vehicles is PCV oil not oil from turbo seal leaks.

My theory is that CBU on low mileage (less than 80k) vehicles probably occurs in vehicles driven under moderately hard acceleration where more soot is make and recirculated with the EGR.

If my theory is right, the risk of CBU can be reduced by accelerating slower so less soot is made. If you don't make soot it isn't available to become CBU. You will also reduce CBU by putting a coalescing filter on the PCV, venting the PCV to the air instead of the intake or both.

[Pierre Louis]

Nice to read your thoughts.

Originally Posted by Tomnavigator

The harder you accelerate the more soot is produced. Under light loads none make visible soot.

This may be just a way for the soot that accumulates in the exhaust (visible in cars without DPF) to get out. If you do a wide open throttle downshift, it will give a plume of black smoke, but not the second time if you do it again. Try it.

I saw a BMW chart showing EGR vs engine load. This chart showed that EGR does not occur under wide open throttle. The charts shows that EGR occurs under most engine load conditions.

Which is it? WOT causing the EGR to shut down or not?

I would like to address the stated sources of oil in the intake. 1) (PCV) positive crankcase ventilation, 2) turbo seal leaks 3) valve seal leaks
1) PCV occurs on all vehicles even new ones
2) turbo seals don't normally leak on relatively new vehicles
3) valve seals don't normally leak on relatively new vehicles and typically leak when the intake is under a vacuum. This does not occur on diesels. With the turbo, the intake is under positive pressure at all times. Also, CBU occurs in the intake system long before the area around the valves. Thus valve seal leakage is probably not a significant source of oil causing CBU.
CBU seems to start occurring on vehicles with around 50k miles. Therefore, the probable source of oil in the intake on low mileage vehicles is PCV oil not oil from turbo seal leaks.

I personally don't have much trust in dealerships when it comes to using the proper oil (experience with GM dealers, some mechanics, that think oil is oil and should be changed every X,000 miles, and comes out of one barrel in the back) so it may also be how the blowby oil interacts in the combustion chamber, and believe there are even more factors involving CBU than just mechanical leaks etc.

I also think that base stock diesel varies a lot based on oil source (sweet crude vs oil from tar sands, for example) and that metallic additives and contaminants may also contribute. Think about it: fuel injector cleaners work by replacing the deposit with a metallic additive that adheres to the injector more strongly. In a previous post, I mentioned a paper that alludes to certain metal-based additives cause more CBU.

PL

[DWR]

Originally Posted by Tomnavigator

3) valve seals don't normally leak on relatively new vehicles and typically leak when the intake is under a vacuum. This does not occur on diesels.

Just to keep the facts straight the 335d does have vacuum in the intake.

[TDIwyse]

Originally Posted by Pierre Louis

...Those that get rid of their EGR/DPF etc. will put on a bunch of miles and hopefully will not be bothered by it. We shall see.

PL

Hooper, didn't you post pics of your intake showing a reversal in carbon buildup after blocking EGR and using H2O/methanol injection?

An interesting comparison of EGR vs CBU is on the Dodge Cummins engine family. For example, in 2003/4 the Cummins Common Rail trucks did not use EGR of any kind, and were able to meet emission requirements. I have an 04, and the oil stays clean throughout the 15k mile oil change intervals and no visible signs of carbon buildup when looking at the intake grid heater or the intake tract. In 04.5 they had to move to an "in cylinder" EGR strategy by changing the cam profile, but not EGR through the intake track. Then in 07 time frame they had to move to full EGR along with the rest of the emissions stuff ...

I don't recall hearing much, if any, issues with CBU in the intake system on trucks that did not have EGR routed through the intake. But from 07 on it was fairly frequent topic on the sites I hung out on...

If someone could get the data from Cummins on CBU vs engine year it would be a pretty good of an apples to apples comparison...

[melonbread]

Originally Posted by Tomnavigator

My theory is that CBU on low mileage (less than 80k) vehicles probably occurs in vehicles driven under moderately hard acceleration where more soot is make and recirculated with the EGR. .

why does all mechanics recommend you drive your 335d hard to avoid CBU?

[Hoooper]

Originally Posted by TDIwyse

Hooper, didn't you post pics of your intake showing a reversal in carbon buildup after blocking EGR and using H2O/methanol injection?

yeah there was a clear and significant difference. Pictures taken about 13k miles apart.

Originally Posted by melonbread

why does all mechanics recommend you drive your 335d hard to avoid CBU?

Because they dont know what theyre talking about. Or, theyre throwing stuff at the wall just to see what sticks.

[floydarogers]

Originally Posted by Hoooper

...There have been plenty of cases in CA, theres no evidence to support that there is lower CBU in CA or CA emissions states than other states.

Not totally doubting you, but where is your data to support this assertion? You know what is said about anecdotal-based statistics: worthless.

Here's how I would respond if your assertion were known to be anecdotal: "Well, here in WA/Seattle, the only 335d known is mine, which has had no CBU problem at 96K. Ergo, no CBU exists in WA state, a CA emissions state with good quality diesel. My original speculation is thereby certainly valid, and possibly true."

[Hoooper]

Originally Posted by floydarogers

Not totally doubting you, but where is your data to support this assertion? You know what is said about anecdotal-based statistics: worthless.

Here's how I would respond if your assertion were known to be anecdotal: "Well, here in WA/Seattle, the only 335d known is mine, which has had no CBU problem at 96K. Ergo, no CBU exists in WA state, a CA emissions state with good quality diesel. My original speculation is thereby certainly valid, and possibly true."

We know there have been plenty of cases in CA because plenty of people from CA have posted in this very forum about their CBU. You cant be serious

[floydarogers]

Originally Posted by Hoooper

We know there have been plenty of cases in CA because plenty of people from CA have posted in this very forum about their CBU. You cant be serious

I'm Very serious. I don't look at the location of every poster, nor am I keeping track of every report, nor am I keeping track of the percentage of Californians owning 335d/X5d, nor do I (maybe the mods can find it but I can't) know the percentage of members of E90post in CA owning 335d/X5d.

Just because YOU say "many cases in CA" doesn't mean your characterization or assertion is accurate. There were, after all, about 10,000 335d's sold in the US - CA has about 10% of the cars in the US - which means 1000 335d's if the distribution were even. There have not been even 100 postings here of people having CBU cleaning done, let alone in CA. Come on, you have no idea of the percentage of 335d/X5d having had CBU cleaning done - not even BMW knows for sure, since some percentage is not done in their service bays. Further, you have no idea of the number in the non-CA states, nor do you even have an idea about the other 12 CA states. In short, your statement appears to be complete cra$. In a friendly way, of course. I'm willing to accept that the CBU situation has reached a level of non-significance, definitely to the people owning the cars, and certainly to BMW: they did, after all, come up with a cleaning method. But what "non-significance" means wrt percentages is far from clear, and your use of "many" wrt CA cars is very ambiguous.

[Thisonegoestoeleven]

FWIW I did my cleaning at 100k or so as preventative, but they said it was "pretty bad". The car did almost exclusively highway. First 60k were in Louisiana, the next 35k were in Colorado and Wyoming. Lots of cross country road trips interspersed. 34mpg average with a mix of fairly spirited driving and highway loafing at 2k rpm in 6th. I had a slight mpg dip(32 mpg) when I got into the high 90k's, so I figured it was time to get a clean slate.

[Yozh]

Originally Posted by floydarogers

Not totally doubting you, but where is your data to support this assertion? You know what is said about anecdotal-based statistics: worthless.

Here's how I would respond if your assertion were known to be anecdotal: "Well, here in WA/Seattle, the only 335d known is mine, which has had no CBU problem at 96K. Ergo, no CBU exists in WA state, a CA emissions state with good quality diesel. My original speculation is thereby certainly valid, and possibly true."

May I ask if you had a chance to physically inspect your intake for CBU evidence. I, personally can not say whether my car has or does not have CBU. I have never looked.